All living things, from tiny cyanobacteria to giant blue whales, need water to survive. Without water, life as we know it would not exist.
And life exists wherever there is water.

All organisms, like animals and plants, use water: salty or fresh, hot or cold, plenty of water or almost no water at all. They are adapted to all kinds of habitats, from sizzling deserts to the freezing,
pitch-dark ocean floor. The first living things appeared in the ocean nearly four billion years ago. Some, like our ancestors, adapted to life on land. Humans have figured out how to survive in swamps,
deserts, and all kinds of habitats in between.

The ocean is still home to more kinds of life than anywhere else on the planet.